Project Summary Genetic researchers are rapidly adopting methods of whole exome and whole genome sequencing to identify the hereditary bases for human disease as the cost of sequencing rapidly declines and the pipelines for analysis and databases of normal variation become available and more robust. Although most researchers have focused on particular diseases, comprehensive genome analysis also provides data about susceptibility to hereditary conditions beyond the original study aims. Thus, many incidental genetic findings of potential clinical relevance to research participants could be generated by the use of whole exome or whole genome sequencing. Such incidental results could have immediate implications for conditions that are avoidable and clinically actionable, such as risk of sudden cardiac death or cancer, but could also indicate hereditary predispositions for conditions for which there is no intervention, such as Alzheimer's disease. It is currently unclear whether incidental genetic findings should be offered to research participants and, if so, which ones, whether research participants will want these results, how participants will respond to their disclosure, and what is required of investigators to return results. Our goal is to collect data to address these questions. We will collect qualitative and quantitative data to investigate decision preferences for return of incidental genetic results and potential psychosocial and behavioral consequences of this information in a large sample of research participants (n=360) who have previously enrolled in research studies for specific diseases. A subset of this population (n=180) will have whole exome sequencing to attempt to identify the underlying causes of a specific disease and will be offered the option of receiving other broader genetic results of clinical relevance. Participants will undergo a re-consent process for this study and will be provided with the option of selective, comprehensive, or no return of those incidental genetic results with clinical utility. To document the medical and psychosocial impact of return of results, we will conduct surveys of participants who received incidental whole exome sequencing results at one month and 12 months following the return of results and conduct semi- structured interviews at 12 months after disclosure on a subset of 60 participants who were offered return of results. Additionally, we will conduct semi-structured interviews and collect survey data from researchers with genomic data (n=300) to determine current practices and important considerations with respect to return of incidental results. Collectively, these results will provide a more complete picture of the possible benefits and burdens of return of incidental research results to participants, differential responsibilities of the primary and secondary users of genomic data with varying degrees of access to and connection with the research participants, and the range of possible incidental findings that could be reported and the differential responsibility to report these results based upon the clinical and psychosocial implications.